Enhancing Multi-Tenant Applications Security with AWS Lambda’s New Tenant Isolation Mode

In today’s digital landscape, multi-tenant applications have become increasingly prevalent, especially within the realms of Software-as-a-Service (SaaS) platforms. These applications often necessitate stringent separation when it comes to processing tenant-specific code or data. This requirement is particularly crucial for SaaS platforms designed for workflow automation or code execution, where customers need assurance that their execution environments are uniquely isolated from those of other users. Historically, developers have managed these needs by deploying separate AWS Lambda functions for each tenant or by integrating custom isolation logic within shared functions. This approach, while effective, often led to increased architectural and operational complexity.

However, a significant advancement has been made in this area. AWS Lambda has introduced a novel tenant isolation mode that builds upon the existing function-level isolation capabilities. This new mode enhances the isolation by extending it to the individual tenant or end-user level within a single function. This built-in functionality allows for the processing of function invocations in separate execution environments for each tenant, thereby meeting strict isolation requirements without requiring additional efforts to manage tenant-specific resources within function code.

Enabling Tenant Isolation Mode in AWS Lambda

To leverage this new capability, you can enable tenant isolation mode through the AWS Lambda console. This feature allows Lambda to associate function execution environments with customer-specified tenant identifiers. Essentially, this means that the execution environment for a particular tenant will not be used to serve invocation requests from other tenants using the same Lambda function.

This enhancement is particularly beneficial for SaaS providers dealing with sensitive data or running untrusted tenant code. By maintaining the pay-per-use and performance attributes of AWS Lambda while gaining execution environment isolation, developers can now enjoy the security benefits of per-tenant infrastructure. This approach eliminates the operational burden associated with managing dedicated Lambda functions for individual tenants, especially as the customer base grows.

Getting Started with AWS Lambda Tenant Isolation

Here’s a step-by-step guide on how to configure and use tenant isolation for a multi-tenant application:

1. Creating a Function: Start on the "Create function" page in the AWS Lambda console and choose the "Author from scratch" option.
2. Enabling Tenant Isolation Mode: Under "Additional configurations," select "Enable" under "Tenant isolation mode." It’s important to note that tenant isolation mode can only be set during function creation and cannot be modified for existing Lambda functions.
3. Writing the Code: You can write your function code, such as in Python, to utilize this capability. The tenant identifier can be accessed in your function code through the context object.

   “`python
   import json
   import os
   from datetime import datetime

   def lambda_handler(event, context):
   tenant_id = context.tenant_id
   file_path="/tmp/tenant_data.json"

   Read existing data or initialize
   

   if os.path.exists(file_path):
   with open(file_path, ‘r’) as f:
   data = json.load(f)
   else:
   data = {
   ‘tenant_id’: tenant_id,
   ‘request_count’: 0,
   ‘first_request’: datetime.utcnow().isoformat(),
   ‘requests’: []
   }

   Increment counter and add request info
   

   data[‘request_count’] += 1
   data[‘requests’].append({
   ‘request_number’: data[‘request_count’],
   ‘timestamp’: datetime.utcnow().isoformat()
   })

   Write updated data back to file
   

   with open(file_path, ‘w’) as f:
   json.dump(data, f, indent=2)

   Return file contents to show isolation
   

   return {
   ‘statusCode’: 200,
   ‘body’: json.dumps({
   ‘message’: f’File contents for {tenant_id} (isolated per tenant)’,
   ‘file_data’: data
   })
   }
   “`

4. Deploying and Testing the Function: Once the code is complete, deploy the function. Testing this capability involves creating a new test event where there’s a new setting called "Tenant ID." If you try to invoke the function without a tenant ID, you’ll encounter an error message prompting you to add a valid tenant ID.
5. Testing with Different Tenant IDs: By testing the function with different tenant IDs, such as "tenant-A" and "tenant-B," you can observe how the function maintains separate execution environments for each tenant. This means that cached data, global variables, and any files stored in /tmp are isolated per tenant.
   

   Additional Information and Benefits
   

   • Performance: Invocations from the same tenant can still benefit from warm execution environment reuse, ensuring optimal performance.
   • Pricing: Charges apply when Lambda creates a new tenant-aware execution environment. The cost depends on the memory allocated to your function and the CPU architecture used. More details can be found in the AWS Lambda pricing guide.
   • Availability: This feature is available in all commercial AWS Regions, except for Asia Pacific (New Zealand), AWS GovCloud (US), and China Regions.

     This new tenant isolation mode simplifies the process of building multi-tenant applications on AWS Lambda, making it particularly useful for SaaS platforms focused on workflow automation or code execution. For more detailed instructions on configuring tenant isolation for your next multi-tenant Lambda function, refer to the AWS Lambda Developer Guide.

     The introduction of tenant isolation mode represents a significant advancement in how developers can approach multi-tenant serverless architecture, reducing the complexity of isolation patterns and the need for managing numerous tenant-specific Lambda functions. This feature ensures that tenant data remains segregated and secure, providing developers with enhanced confidence in the security and separation of their multi-tenant applications.

For more Information, Refer to this article.